public (ulong move, int score) Solve(Position P, int depth)
{
var realDepth = Math.Min(depth, (Position.HEIGHT * Position.WIDTH - P.Moves));
if (realDepth < depth)
{
Console.WriteLine($"Search depth reduced to {realDepth}");
}
var color = P.PlayerToMove == Player.PlayerA ? 1 : -1;
var bestScore = Int32.MinValue;
ulong bestMove = 0;
var allMoves = P.GetMoves().ToList();
foreach (var move in allMoves)
{
Position p2 = new Position(P);
p2.Play(move);
var value = -Negamax(p2, realDepth - 1, Int32.MinValue, Int32.MaxValue, -color);
if (value > bestScore)
{
bestScore = value;
bestMove = move;
}
}
Console.WriteLine(bestScore);
return(bestMove, bestScore);
}
} // counter of explored nodes.
int Negamax(Position P, int depth, int alpha, int beta, int color)
{
if (P.ConnectedFour(P.CurrentPosition))
{
return(color * (1000 + EvaluateNode(P)));
}
if (P.Moves >= 42)
{
return(0);
}
if (depth == 0)
{
return(color * EvaluateNode(P));
}
NodeCount++;
int best = Int32.MinValue;
foreach (var move in P.GetMoves())
{
Position p2 = new Position(P);
p2.Play(move);
best = Math.Max(best, -Negamax(p2, depth - 1, -beta, -alpha, -color));
alpha = Math.Max(alpha, best);
if (alpha >= beta)
{
break; // prune the exploration if we find a possible move better than what we were looking for.
}
}
return(best);
}
public async Task MachineVsMachine(int depth)
{
//player 1 is human
//player 2 is machine
Console.WriteLine("Match started....\n");
var solver = new Solver();
var position = new Position();
bool player1ToPlay = true;
while (true)
{
Console.WriteLine($"Number of nodes processed: {solver.NodeCount}");
if (position.Moves >= 42)
{
Console.WriteLine("Game ended in a draw");
return;
}
if (player1ToPlay) //Machine 1 to play
{
Console.WriteLine("Player 1 thinking about a move...");
await Task.Delay(500);
(ulong move, int score) = solver.Solve(position, depth);
SB.AppendLine($"Score = {score}");
PrintColumnPlayed(move, position.PlayerToMove);
position.Play(move);
}
else //Machine 2 to play
{
Console.WriteLine("Player 2 thinking about a move...");
await Task.Delay(500);
(ulong move, int score) = solver.Solve(position, depth);
SB.AppendLine($"Score = {score}");
PrintColumnPlayed(move, position.PlayerToMove);
position.Play(move);
}
var player1 = position.PlayerToMove == Player.PlayerA ? position.CurrentPosition : position.CurrentPosition ^ position.Mask;
var player2 = position.PlayerToMove == Player.PlayerB ? position.CurrentPosition : position.CurrentPosition ^ position.Mask;
if (position.GameWon())
{
Console.WriteLine("Position is won");
var gameWon = Utils.FillBoardWithPlayersTag(player1, player2);
Console.WriteLine(gameWon);
break;
}
var game = Utils.FillBoardWithPlayersTag(player1, player2);
Console.WriteLine(game);
SB.AppendLine(game);
player1ToPlay = !player1ToPlay;
}
var whoWon = player1ToPlay ? "Player 1 won!" : "Player 2 won";
Console.WriteLine(whoWon);
//only used for loggging of whole game
//var path = @"c:\utvikling\connect4.txt";
//File.WriteAllText(path, SB.ToString());
}
public async Task HumanVsMachine(int depth)
{
//player 1 is human
//player 2 is machine
Console.WriteLine("Match started....\n");
var solver = new Solver();
var position = new Position();
bool player1ToPlay = true;
while (true)
{
if (position.Moves >= 42)
{
Console.WriteLine("Game ended in a draw");
break;
}
if (player1ToPlay) //human to play
{
if (position.CurrentPosition == 0)
{
var pos = Utils.FillBoardWithPlayersTag(position.CurrentPosition, position.CurrentPosition ^ position.Mask);
Console.WriteLine("Startposition with 6 rows and 7 columns");
Console.WriteLine(pos);
}
Console.WriteLine("Player A: \nChoose a move between 1 .. 7");
var col = Console.ReadLine();
var cmd = Convert.ToInt32(col) - 1;
if (position.CanPlay(cmd))
{
position.PlayCol(cmd);
}
else
{
Console.WriteLine($"The move to col {cmd + 1} is not allowed");
}
}
else //computer AI
{
Console.WriteLine("Computer thinking about a move...");
Console.WriteLine(position.PlayerToMove);
await Task.Delay(500);
(ulong move, int score) = solver.Solve(position, depth);
SB.AppendLine($"Score = {score}");
PrintColumnPlayed(move, position.PlayerToMove);
position.Play(move);
}
var player1 = position.PlayerToMove == Player.PlayerA ? position.CurrentPosition : position.CurrentPosition ^ position.Mask;
var player2 = position.PlayerToMove == Player.PlayerB ? position.CurrentPosition : position.CurrentPosition ^ position.Mask;
if (position.GameWon())
{
Console.WriteLine("Position is won");
var gameWon = Utils.FillBoardWithPlayersTag(player1, player2);
Console.WriteLine(gameWon);
break;
}
var game = Utils.FillBoardWithPlayersTag(player1, player2);
Console.WriteLine(game);
SB.AppendLine(game);
player1ToPlay = !player1ToPlay;
}
var whoWon = player1ToPlay ? "You won!" : "Computer won";
Console.WriteLine(whoWon);
//only used for loggging of whole game
//var path = @"c:\utvikling\connect4.txt";
//File.WriteAllText(path, SB.ToString());
}